The invention concerns drive arrangements for signal-processing devices, especially information-storage-disk devices. Such drive arrangements may comprise a collectorless D.C. motor having a permanent-magnet external rotor serving for direct-drive of an information-storage disk, the internal stator of the motor comprising a carrier structure which accommodates roller bearing units for the rotor shaft, the carrier structure being provided with a mounting portion for mounting the motor as a whole. A packet of stator plates is provided radially outward of the carrier structure and the rotor shaft is journalled in the roller bearing units within the carrier structure. Such an arrangement is described in U.S. patent application Ser. No. 440,537, now U.S. Pat. No. 4,604,665, commonly owned, the disclosure of which is incorporated herein by reference.
Motors of this or similar types are used as drives in high-precision devices and exhibit many outstanding characteristics. However, for many types of applications motors of more compact construction would be required.